Mixer assembly

ABSTRACT

A mixer comprises a tubular housing defining a longitudinal axis along which exhaust gas flows. Injected reductant flows along an injection axis that extends at a non-parallel angle to the longitudinal axis. A first flow guide element extends across and blocks a portion of the tubular housing and includes a first aperture extending therethrough. The first flow guide element is positioned upstream from the reductant inlet such that exhaust gas flowing through the first aperture is impinged by the reductant. A second flow guide element is positioned downstream from the first flow guide element and fixed to the first flow guide element to define a mixing chamber in which injected reductant and exhaust gas mix. An intermediate wall is integrally formed with one of the first and second flow guide elements. The other of the first and second flow guide elements is fixed to the intermediate wall.

FIELD OF THE INVENTION

The invention relates to a mixing device for integration or connectionor coupling to an exhaust pipe or connection to an exhaust pipe of acombustion engine and for mixing an exhaust gas stream T, which isformed from a housing having a tubular wall with a round or oval profileQ and a mid-axis that can be aligned parallel to the exhaust pipe andfrom an intermediate wall which is aligned transversely to the mid-axis,wherein the intermediate wall divides the housing and features an inflowside and an outflow side, and creates a division of the housing into aninflow section and an outflow section, wherein at least one inflowopening E1 is provided in the intermediate wall, through which theexhaust gas stream T can flow at least partially from the inflow side ofthe intermediate wall to an opposite outflow side of the intermediatewall, wherein the at least one inflow opening E1 is positionedeccentrically with respect to the mid-axis and is brought close to awall section W1 of the tubular wall.

The invention further relates to a mixing device for connection to orintegration into an exhaust pipe of a combustion engine and for mixingan exhaust gas flow T, which is formed from a housing with a tubularwall with a round or oval profile Q and with a mid-axis that can bearranged parallel to the exhaust pipe and with a first intermediate wallZ1 and with a second intermediate wall Z2 which are aligned transverselyto the mid-axis, wherein both intermediate walls Z1, Z2 at least partlybound a mixing chamber, wherein the first intermediate wall Z1 featuresat least one inflow opening E1, through which the exhaust gas stream Tcan enter the mixing chamber, wherein the inflow opening E1 ispositioned eccentrically with respect to the mid-axis and is broughtclose to a wall section W1 of the tubular wall, and the secondintermediate wall Z2 features at least one outflow opening A1, throughwhich the exhaust gas stream T can exit from the mixing chamber, whereinthe outflow opening A1 is positioned eccentrically with respect to themid-axis and is brought close to a wall section W2 of the tubular wall.

The exhaust pipe can also be the corresponding part of the housing for acatalytic converter or particle filter.

The mixing relates to an additive to be incorporated, such as areduction agent or hydrocarbon compounds.

The housing usually has a round profile Q. Alternatively, said housingcan also feature an oval or polygonal profile Q.

For the purpose of forming an inflow opening E or an outflow opening A1,a recess is always required within an intermediate wall that closes theprofile area QF of the housing. This can be achieved according to theexemplary embodiments through the use of a correspondingly smallintermediate wall, which is reduced in diameter over a portion of thecircumference.

BACKGROUND OF THE INVENTION

A mixing device for connection to an exhaust pipe of a combustion enginefor mixing an exhaust gas stream is already known from WO 2012/080585A1. This features a housing with a tubular wall with a round profile anda mid-axis that can be aligned parallel to the exhaust pipe, and anintermediate wall with an inflow opening which is essentially alignedtransversely to the mid-axis. The intermediate wall has a coiled shape,so that the entire exhaust gas stream is deflected in the samecircumferential direction. Additionally, a downstream secondintermediate wall is provided with an outflow opening, which together atleast partially bound a mixing chamber.

A mixing device is known from U.S. Pat. No. 8,033,104 B2, which featuresa perforated intermediate wall that lies transverse to the exhaust pipeand a feed channel for reduction agent. A portion of the exhaust gasstream mixes with the reduction agent while flowing through theperforated feed channel. A second portion of the exhaust gas is notguided through the feed channel, but flows through the perforation ofthe intermediate wall and thus reaches the exit of the mixing device.

In DE 10 2013 012 909 A1, a mixing chamber is described which features atubular flow guide element, through which the exhaust gas stream isguided from an entrance opening of the mixing chamber to an exitopening, wherein the axis of the flow channel lies transversely to themid-axis of the mixing chamber. At one end of the flow guide element, anadditive can be injected so that said additive mixes with the exhaustgas in the tubular channel.

FR 2 943 381 A1 describes a tubular mixing element with threeintermediate walls, wherein the middle intermediate wall is arrangedopposite the first and last intermediate wall with respect to themid-axis.

WO 2014 051617 A1 also describes a mixing device which effects adeflection of the exhaust gas stream in the circumferential direction.

DE 10 2012 224 198 A1 describes a classic swirl mixer consisting of amixing sheet with several mixing blades distributed over thecircumference.

SUMMARY OF THE INVENTION

The object of the invention is to design and arrange a mixing device insuch a manner that a good mixing behavior is guaranteed despite thecompact, space-saving construction.

The object is attained according to the invention by the fact that aflow guide element S2 is provided with a longitudinal axis L2, whichwith the intermediate wall at least partly bounds a mixing chamber, andby means of which an at least partial deflection of the exhaust gasstream T can be effected from its original flow direction into a radialdirection in relation to the mid-axis or the housing, wherein the flowguide element S2 features at least two outflow openings A1, A2, and bymeans of the flow guide element S2, the exhaust gas flow T can beguided, starting from the inflow opening E1 to the at least two outflowopenings A1, A2, wherein all outflow openings A1, A2 are positionedeccentrically with respect to the mid-axis and are brought close to awall section W2 of the tubular wall, wherein the wall section W2 isarranged opposite the wall section W1 with respect to the mid-axis, andthe outflow openings A1, A2 are arranged on opposite sides of the flowguide element S2 with respect to the longitudinal axis L1, L2, whereinwith respect to the mid-axis, a first partial stream T3 can be guided atleast partially in the anticlockwise direction and a second partialstream T4 can be guided at least partially in the clockwise directionout of the outflow openings A1, A2. Due to the arrangement of theoutflow openings A1, A2 on opposite sides of the flow guide element S2,a bridge is formed.

The object is also attained according to the invention through the factthat the wall section W2 is arranged opposite the wall section W1 withrespect to the mid-axis, so that an at least partial deflection of theexhaust gas stream T can be effected at least partially in a radialdirection with respect to the mid-axis, and in the flow direction afterthe first intermediate wall Z1 or before the second intermediate wall Z2in the area of the outflow opening A1, at least one flow guide elementS3 is provided in the mixing chamber, which protrudes in the radialdirection over the tubular wall and effects a division of the exhaustgas stream T into two partial streams T3, T4, wherein with respect tothe mid-axis, a first partial stream T3 can be guided in theanticlockwise direction, and a second partial stream T4 can be guided ina clockwise direction around the flow guide element S3. Duringoperation, the flow guide element S3 guides the first partial stream T3in an anticlockwise direction and the second partial stream T4 in aclockwise direction.

The inflow opening E1 lies opposite the respective outflow opening A1,A2 with respect to the mid-axis. In relation to a symmetrical axis,which runs transversely to the mid-axis or at right-angles to a plane LEwhich spans through the mid-axis and longitudinal axis L2, the inflowopening E1 is positioned between the symmetrical axis Sy and the wallsection W1, while the respective outflow opening A1, A2 is positionedbetween the symmetrical axis Sy and the wall section W2. Due to theopposite arrangement of the inflow and outflow openings E1, A1, A2 withrespect to the mid-axis, a deflection of the exhaust gas flow T isachieved in a radial direction to the pipe. This in turn supports thefunction of the flow guide element S2, S3, which effects thecounter-directional deflection in the circumferential direction, i.e. ina clockwise direction and an anticlockwise direction.

It has been shown in studies that the deflection of the entire exhaustgas stream into a single swirl flow moving in the same direction in thecircumferential direction leads to a disadvantageous interaction withthe housing wall of the mixing device, such as condensation or thecrystallization of an additive that has also been transported. Throughthe use of a flow guide element, which divides the exhaust gas streamand conducts a circumferential movement in the opposite direction, incombination with a flow deflection of the entire exhaust gas stream intoa radial direction, the circumferential speed is in general lower, whichalso leads to lower centrifugal forces. Therefore, the aerosols of theadditive transported in the exhaust gas stream are added lessintensively to the housing wall, as a result of which the degree ofcondensation or crystallization is reduced considerably. The deflectionin the opposite direction leads to a further mixing of the exhaust gasstream. Here, the flow conditions at the outflow opening A1 areinitially of importance for the division of the exhaust gas stream andthe respective deflection. A division applied upstream in the area ofthe inflow opening E1 of the exhaust gas stream and/or its deflection inthe circumferential direction can be advantageous, as described below.

In this regard, it can be advantageous when on the intermediate wall afirst flow guide element S1 with a longitudinal axis L1 is provided,which protrudes upstream in the axial direction over the intermediatewall and which with the intermediate wall at least partly bounds themixing chamber, wherein two inflow openings E1, E2 are provided in theintermediate wall, which are arranged opposite in relation to thelongitudinal axis L1 or the plane LE, wherein the flow guide element S1effects a division of the exhaust gas stream T into two partial streamsT1, T2, wherein with respect to the mid-axis, a first partial stream T1can be guided in a clockwise direction and a second partial stream T2can be guided in an anticlockwise direction around the flow guideelement S1 into the respective inflow opening E1, E2 and into the mixingchamber. The exhaust gas stream is therefore already divided when itenters the mixing chamber and is deflected in the circumferentialdirection, so that mixing is further improved. Due to the arrangement ofthe inflow openings E1, E2 on opposite sides of the flow guide elementS1, a bridge is formed.

For this purpose, it can also be advantageous when the flow guideelements S1, S2 are designed as a single piece and/or when at least oneflow guide element S1, S2 is an integrated part of the intermediate walland/or the tubular wall. The combination of an intermediate wall with apipe that runs diametrically within it, which forms the flow guideelement S1, S2 and bounds the mixing chamber, appears to beadvantageous.

It can further be advantageous when the inflow opening E1, E2 and/or theoutflow opening A1, A2 extends at least partially or fully onto the flowguide element S1, S2 or is provided in the flow guide element S1, S2.

An inflow opening is required through which the exhaust gas canpenetrate. Depending on the design of the mixing chamber, said chamberis arranged within the intermediate wall. Insofar as the flow guideelement S1 is an integral part of the intermediate wall, it remains inthe intermediate wall near the inflow opening. Only the positioning ofthe inflow opening can be changed in such a manner that the flow guideelement S1 is covered. If the flow guide element S1 is a separatecomponent, which is positioned on the intermediate wall, an inflowopening must be provided both in the intermediate wall and the flowguide element S1. The same applies to the outflow openings.

If the flow guide element S1 is an integral part of the intermediatewall, no further intermediate wall is required for the flow guideelement S2, i.e. the flow guide element S2 can be designed as a separatecomponent which is positioned on the one intermediate wall. In anequivalent manner, the flow guide element S2 can also be an integralcomponent of the intermediate wall, so that the flow guide element S1 isdesigned as a separate component.

Finally, it is also possible to provide two intermediate walls and forthe respective flow guide element S1, S2 to be an integral part of therespective first or second intermediate wall.

Here, it can advantageously be provided that the intermediate wall andthe mid-axis enclose an angle α between 20° and 80°, or between 30° and60°, or between 55° and 75°, or of 65°. The angle between theintermediate wall and the mid-axis determines the ratio between theprofile size or housing height and the construction length or housinglength. Since the shortest possible construction length of the mixingdevice is desired, angles between 55° and 75° are particularlyadvantageous. In relation to the intermediate wall, the straight line Gshould be taken as a reference, which also results from the connectionof the two furthest upstream and downstream connection points of theintermediate wall with the tubular wall.

For this purpose, it can be advantageous when the intermediate wall hasa single or multiple angles, contoured or curved form, such as an L, a Zor an S form. The intermediate wall can also be designed asymmetricallywith respect to the plane LE.

It can additionally be advantageous when in the mixing chamber in thearea before the outflow openings A1, A2, for the purpose of avoiding asteam bottleneck, a corrugated base and/or a flow guide element such asa cone or a semi-cone or a ramp is provided.

It can additionally be advantageous when the intermediate wall is atleast partially integrated into the housing or is formed at leastpartially from the housing.

It can additionally be advantageous when a feed device is fitted with afeed nozzle, through which an additive can be brought into the mixingchamber. When the additive has already been mixed into the exhaust gasstream, an improved mixing can be achieved by the mixing device.Naturally, the mixing in is also provided within the mixing device.Here, it is provided that the additive is injected at an angle ofbetween 5° and 185°, and thus e.g. the inner walls of the mixing chamberare used for atomizing and evaporating the additive.

It can also be advantageous when the inflow opening E1 and/or the inflowopenings E1, E2 form an inflow profile QE and the housing features aprofile surface QF that effects the stream, with 0.08 QF<=QE<=0.42 QFThe inflow profile therefore moves between 8% and 42% of the pipeprofile or housing profile. This entails sufficient acceleration of theexhaust gas on the one hand and acceptable pressure losses on the other.

Accordingly, it can be advantageous when the outflow opening A1 and/orthe outflow openings A1, A2 form an outflow profile QA and the housingfeatures a profile surface QF that affects the stream, with 0.08QF<=QA<=0.42 QF.

It can additionally be advantageous when the inflow opening E1 or theinflow openings E1, E2 form an inflow profile QE and at least onefurther inflow opening Ex is provided in the flow guide element S1 or inthe intermediate wall Z1, through which a portion of the exhaust gasstream T can enter the mixing chamber, wherein the at least one inflowopening Ex forms an inflow profile Xe, with Xe<=0.1 QE.

It can additionally be advantageous when the outflow opening A1 or theoutflow openings A1, A2 form an outflow profile QA and at least onefurther outflow opening Ax is provided in the flow guide element S2 orin the intermediate wall Z2, through which a portion of the exhaust gasstream T can enter the mixing chamber, wherein the at least one outflowopening Ax forms an outflow profile Xa, with Xa<=0.1 QE.

As a supplement to the inflow and outflow openings E1, E2, A1, A2,further openings Ex, Ax can be provided. While the positioning of theinflow and outflow openings E1, E2, A1, A2 is designed according to theinvention in such a way that a deflection of the exhaust gas stream in aradial direction to the pipe is achieved, further openings Ex, Ax can bepositioned as required. Preferably, however, openings Ex are arranged inthe area of the bridge of the flow guide element S1 so that the entireexhaust gas stream flows into the mixing chamber.

Additionally, outflow openings Ax can be arranged in the area of thebridge of the flow guide element S2. The value Xe is the perforationprofile, i.e. the total of the profiles of all inflow openings Ex, andthe Xa value is the total of the profiles of all outflow openings Ax.Preferably, 0.03 A<=Xa<=0.07 A or 0.03 E<=Xe<=0.07 E applies.

It can also be advantageous when a stream blade is provided on at leastone inflow opening Ex and/or on at least one outflow opening Ax. Inorder to avoid a stream bottleneck in this area, or for improvedalignment of the auxiliary stream guided through the inflow opening Exand/or the outflow opening Ax, said auxiliary stream can be deflected bythe blades in the radial direction and/or in the circumferentialdirection.

Additionally, it can be advantageous when in the mixing chamber at leastone static mixer or a mixer pipe and/or at least one even or angled orcurved baffle plate is provided, wherein the baffle plate is largelyarranged parallel to the longitudinal axis L1, L2 of the flow guideelement S1, S2. The baffle plate can be fitted with a hydrolysis coatingwhich supports the disintegration or transformation of the additive. Ananti-adhesion coating or anti-adhesion surface structure is alsoprovided. Advantageously, the baffle plates are arranged in such amanner that a low level of additional pressure loss is generated. Thisis achieved by the fact that the plates are arranged almost parallel tothe flow direction in the mixing chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and details of the invention are explained in thepatent claims and in the description and figures, in which:

FIG. 1 a shows a profile view of the principle sketch of the mixingdevice from the front;

FIG. 1 b shows the mixing device shown in FIG. 1 a from the rear;

FIG. 2 a, 2 b show the respective profile view A-A or B-B according toFIG. 1 a;

FIG. 3 a shows the mixing device with exhaust pipe;

FIG. 3 b shows the dividing wall with single-part flow guide element S1,S2;

FIG. 4 shows an alternative embodiment in a perspective view;

FIG. 5 a shows the mixing device shown in FIG. 4 from the rear;

FIG. 5 b shows the profile view C-C shown in FIG. 5 a;

FIG. 6 shows a profile view of a schematic sketch without mixing pipe.

DETAILED DESCRIPTION OF THE INVENTION

The mixing device 1 shown in FIG. 1 a features a tubular housing 2 witha round profile Q. Within this housing 2, an intermediate wall 3 isprovided which is set at an angle α opposite a mid-axis 2.2 (see FIG. 2a, 2 b ). On the intermediate wall 3, a flow guide element S1 isprovided which extends upstream with respect to the direction of theexhaust gas (to the left according to FIG. 2 ) from the intermediatewall 3. The flow guide element S1 features two inflow openings E1, E2,through which an exhaust gas flow T (see FIG. 3 a ) can flow from theinflow side 3.1 shown in FIG. 1 a of the intermediate wall 3 to therearward outflow side 3.2. The surface of the flow guide element S1increases upwards, so that there is sufficient space for the inflowopenings E1, E2 mentioned above. A bridge 2.6 is formed between the twoinflow openings E1, E2. As a result of the bridge 2.6, said exhaust gasflow T is divided into two partial streams T1, T2. The partial stream T1flows in a clockwise direction and the partial stream T2 flows in ananticlockwise direction into the respective inflow opening E1, E2. Withrespect to a symmetrical axis Sy, which according to FIG. 1 a dividesthe housing 2 approximately in the middle and horizontally, the twoinflow openings E1, E2 are moved towards the upper wall section W1,additionally the flow guide element S1 features a further inflow openingEx, through which a small portion of the exhaust gas can flow from theinflow side 3.1 to the outflow side 3.2 of the intermediate wall 3.

The outflow side 3.2 of the intermediate wall 3 is according to FIG. 1 bmirror symmetric to the symmetry axis Sy. There, the flow guide elementS2 is located, which extends in the direction of the exhaust gas flow(to the right according to FIG. 2 ) over the intermediate wall 3. Theflow guide element S2 features two outflow openings A1, A2, which aredisplaced downwards with respect to the symmetry axis S2 to a wallsection W2. Both flow guide elements S1, S2 feature a longitudinal axisL1, L2, which according to the exemplary embodiment runs central to thepipe wall 2.1 or at right-angles to a mid-axis 2.2 of the pipe wall 2.1.Further outflow openings Ax are provided in the intermediate wall 3,which are positioned opposite the outflow openings A1, A2 with respectto the symmetry axis Sy. A bridge 2.4 is also formed between the twooutflow openings A1, A2, so that the exhaust gas stream T exits in twopartial streams T3, T4, wherein the partial stream T3 leaves the flowguide element S2 in an anticlockwise direction and partial stream T4leaves in a clockwise direction. Additionally, the flow guide element S2features further outflow openings Ax in the area of the bridge 2.4. Aflow blade 9.2 is provided on the respective outflow opening Ax, throughwhich the auxiliary stream that flows through the outflow opening Ax canbe deflected in a radial direction.

Both flow guide elements S1, S2 bound a mixing chamber 2.3, which due tothe opposite arrangement of the inflow openings E1, E2 on the one handand the outflow openings A1, A2 on the other is predominantly flowedthrough by the exhaust gas stream T in the radial direction.

As can be seen in FIG. 3 a , a feed device 5 with a feed nozzle 5.1 islocated within the mixing chamber 2.3, through which an additive isintroduced into the exhaust gas stream T.

In the profile view A-A shown in FIG. 2 a , the flow guide element S1and the flow guide element S2 can be seen in profile. The exhaust gasthat flows in here from the left enters into the inflow opening E1 orinto the additional opening Ex into the mixing chamber 2.3 and leavessaid chamber via the outflow opening A1. Within the mixing chamber 2.3,a corrugated base 7 is arranged below the outflow opening A1transversely to the main flow direction, which prevents the formation ofa stream bottleneck in the area of the outflow opening A1. Additionally,within the mixing chamber 2.3, a baffle plate 2.5 is provided, which canbe moistened with additive through the nozzle 5.1 not shown here.

In the profile view B-B according to FIG. 2 b , only the intermediatewall 3 is profiled, while the two flow guide elements S1, S2 can be seenin a side view. The opposite inflow openings E1, E2 can be seen, as canthe two outflow openings A1, A2. The intermediate wall 3 is set oppositethe mid-axis 2.2 and the angle α. The exhaust gas stream that comes fromthe left here is largely deflected upwards in the radial directiontowards the inflow openings E1, E2 and in turn flows through the mixingchamber 2.3 in the radial direction from the inflow openings E1, E2downwards to the outflow openings A1, A2, and leaves the mixing chamber2.3 to the right through the two outflow openings A1, A2 according toFIG. 2 b.

According to FIG. 3 a , the mixing device 1 is an integral part of anexhaust pipe 4.1, 4.2 as part of a particle filter or catalyticconverter. Through the nozzle 5.1, additive is introduced into themixing chamber 2.3, which is guided via the above exhaust gas stream T1or T2, starting from the area of the inflow openings E1, E2 downwards inthe radial direction to the outflow openings A1, A2, and leaves themixing chamber 2.3 through both partial streams T3, T4, and againcombines to form the total stream T. According to FIG. 3 a , as analternative to the corrugated base 7 shown in FIG. 2 , a flow guideelement in the form of a ramp 8 is provided in the area of the outflowopening A1 within the mixing chamber 2.3, so that stream bottlenecks areprevented in this area.

Decisive for the definition of the angle α is the straight line G, whichconnects the intersection points of the intermediate wall 3 and the pipewall 2.1, wherein the two intersection points have the greatest distancefrom each other with respect to the exhaust gas stream or the directionof the mid-axis 2.2.

According to FIG. 3 b , the intermediate wall 3 is shown with asingle-part flow guide element S1, S2 arranged within it. Thesingle-part flow guide element S1, S2 is designed as a cylindrical pipe,which is inserted into a corresponding recess in the oval intermediatewall 3 and which is tightly connected to the intermediate wall 3. Theassembly thus created is then inserted into the housing 2, as shown inFIG. 3 a , wherein the intermediate wall 3 is connected on thecircumference side with the pipe wall 2.1.

FIG. 4 shows an alternative embodiment. Within the housing 2, twointermediate walls Z1, Z2 are provided at a distance with respect to themid-axis 2.2, which extend respectively over approximately half theprofile area QF of the housing 2. The two intermediate walls Z1, Z2 arealso positioned opposite with respect to the two opposite wall sectionsW1, W2, so that the exhaust gas stream T, which enters into the mixingchamber 2.3 through an inflow opening E1, is deflected downwards in theradial direction to the outflow opening A1 and leaves the mixing chamber2.3 through the outflow opening A1. The feed device 5 with the feednozzle 5.1 for additive is also provided within the mixing chamber 2.3or in the housing 2.

A wedge-shaped flow guide element S3 is provided in the area of the wallsection W2, which divides the impinging exhaust gas stream T into twopartial streams T3, T4. Due to the wedge-shaped design of the flow guideelement S3, a partial stream T3 is created with respect to the flowdirection, which is deflected in an anticlockwise direction, while thepartial stream T4 is deflected in a clockwise direction.

According to FIG. 5 a , the mixing device 1 is shown from the outflowside 3.1 (lee side). The mixing chamber 2.3 can only be seen within thescope of the outlet opening A1. In contrast to FIG. 4 , within the upperpart of the mixing chamber 2.3 an optional mixing pipe 6 with aperforation 6.1 is arranged, which is positioned coaxially to the feeddevice 5. The exhaust gas or exhaust gas stream T which flows in throughthe inflow opening, thereby initially flow through the mixing pipe 6within which it then mixes with the sprayed in additive and is guideddownwards towards the flow guide element S3, where the two partialstreams T3, T4 are deflected in the circumferential direction in counterdirections as described above.

Within the second intermediate wall Z2, further slit-shaped outflowopenings Ax are provided, the outflow profile Xa of which is subordinaterelative to the outflow opening A1. These then merely serve to prevent astream bottleneck in the area of the upper wall section W1.Additionally, in the first intermediate wall Z1, further slit-shapedinflow openings Ex are provided, the inflow profile Xe of which issubordinate relative to the inflow profile QE of the inflow opening E1.These serve to prevent a stream bottleneck in front of the firstintermediate wall Z1 in the area of the lower wall section W2. A flowblade 9.1 is provided on the respective inflow opening E1, through whichthe auxiliary stream that flows through the inflow opening Ex can bedeflected in a radial direction.

FIG. 5 b shows the profile view C-C shown in FIG. 5 a. The mixing pipe 6is oval and therefore features an enlarged entrance and exit area facingtowards the exhaust gas stream T. After it has flowed through the mixingpipe 6, the exhaust gas stream T is according to FIG. 5 b deflected inthe radial direction and leaves the mixing device 1 in a divided,counter-directional stream movement outwards in the circumferentialdirection.

In the exemplary embodiment shown in FIG. 6 , the second intermediatewall Z2 is curved. A mixing chamber is not provided. The exhaust gasstream T that enters from the right is deflected downwards in the radialdirection towards the flow guide element S3 after entering the mixingchamber 2.3, and leaves the mixing chamber 2.3 through the outflowopening A1. Here, the height of the flow guide element S3 increases inthe direction of the first intermediate wall Z1, so that the two partialstreams T3, T4 are formed at an early stage.

LIST OF REFERENCE NUMERALS

1 Mixing device

2 Housing

2.1 Tubular wall

2.2 Mid-axis

2.3 Mixing chamber2.4 Bridge between A1, A22.5 Baffle plate2.6 Bridge between E1, E23 Intermediate wall3.1 Inflow side, windward side3.2 Off-flow side, lee side4.1 Exhaust pipe4.2 Exhaust pipe5 Feed device5.1 Feed nozzle6 Mixer, mixer pipe

6.1 Perforation

7 Corrugated base8 Cone, ramp, flow guide element

9.1 Blade of Ex 9.2 Blade of Ax

A1 Outflow openingA2 Outflow openingAx Outflow openingE1 Inflow openingE2 Inflow openingEx Inflow openingG Connection straight line, straight line

LE Plane

L1 Longitudinal axis of S1L2 Longitudinal axis of S2

Q Profile of 2

QA Outflow profileQE Inflow profileQF Outflow areaS1 Flow guide elementS2 Flow guide elementS3 Flow guide elementSy Symmetry axisT Exhaust gas streamT1 Partial stream of exhaust gas streamT2 Partial stream of exhaust gas streamT3 Partial stream of exhaust gas streamT4 Partial stream of exhaust gas streamW1 Wall sectionW2 Wall sectionXa Outflow profile of total AxXe Inflow profile of total ExZ1 Intermediate wallZ2 Intermediate wall

α Angle

1-15. (canceled)
 16. A mixer assembly for mixing an injected reductantwith an exhaust gas output from a combustion engine, comprising: atubular housing including a reductant inlet, an exhaust gas inlet and anexhaust gas outlet, the tubular housing defining a longitudinal axisalong which the exhaust gas flows through the housing, wherein thereductant inlet is oriented to direct injected reductant along aninjection axis that extends at a non-parallel angle to the longitudinalaxis; a first flow guide element extending across the tubular housing toblock a portion of the cross-sectional area of the tubular housing, thefirst flow guide element including a first aperture extendingtherethrough, the first flow guide element being positioned upstreamfrom the reductant inlet such that exhaust gas flowing through the firstaperture is impinged by the injected reductant; a second flow guideelement being positioned downstream from the first flow guide elementand fixed to the first flow guide element to define a mixing chamber inwhich the injected reductant and the exhaust gas mix; and anintermediate wall integrally formed with one of the first flow guideelement and the second flow guide element, wherein the other of thefirst flow guide element and the second flow guide element is fixed tothe intermediate wall.
 17. The mixer assembly of claim 16, wherein thefirst flow guide element includes a second aperture spaced apart fromthe first aperture.
 18. The mixer assembly of claim 17, wherein anexhaust gas flowing through the second aperture is directed toward theinjected reductant.
 19. The mixer assembly of claim 16, wherein thenon-parallel angle is substantially 90 degrees.
 20. The mixer assemblyof claim 16, wherein the second flow guide element includes an exhaustgas outlet positioned downstream from the reductant inlet.
 21. The mixerassembly of claim 16, wherein the first flow guide element is formed asa monolithic one-piece metal panel and the second flow guide element isformed as a monolithic one-piece metal panel.
 22. The mixer assembly ofclaim 16, wherein the exhaust gas upstream of the first flow guideelement flows substantially parallel to the longitudinal axis of thetubular housing, wherein the exhaust gas exiting the mixer assembly isseparated into two divided exhaust streams.
 23. The mixer assembly ofclaim 22, wherein the two divided exhaust streams swirl in oppositedirections to one another.